The present invention relates generally to bearing assemblies and in particular to devices and methods for sealing bearing assemblies used in railway vehicles or other similar applications. Bearing assemblies allow a wheel to rotate relative to a shaft (also called an axle journal). Bearing assemblies are often sealed to maintain a lubricant within the bearing assembly and to prevent dirt, sand, and moisture to enter the bearing assembly. The seal is typically formed of an annular rubber lip seal which rotates about the shaft.
Referring to FIG. 1, a conventional embodiment of a seal 200 for a bearing assembly 100 is shown. The bearing assembly 100 may include, for example, a journal shaft 101 supporting a wear ring 106, an inner race 103, and a backing ring 102. The inner race 103, may support, for example, a tapered roller bearing 105 and a outer race 104. Sealing the grease in the tapered roller bearing is a seal 200 including an upper seal support 202, a lower seal support 209, and a plurality of rubber projections which include: a inner rubber seal 203 having grease seal portion 206, a dust seal 205, and a non-contact side seal 204. The prior art, however, suffers from a number of deficiencies including a propensity for moisture to enter the bearings and degrade the seal.
Accordingly, there exists a need for an improved bearing seal which reduces torque, i.e., is a low-torque seal, while at the same time maintaining the high reliability normally associated with higher torque seals.
Aspects of the present invention overcome one or more of the above-mentioned problems by using improved seal assemblies and/or approved sealing surfaces and/or materials. For example, an aspect of the present invention utilizes a polymeric main seal such that grease is permanently sealed in the tapered roller bearings. In the most preferred embodiments, a Teflon or PTFE is utilized to provide the main seal. The main seal may extend horizontally from a upper seal support and contact and ride along an extended portion of a horizontal lower seal support.
In other aspects of the present invention, a rain shield is provided over the gap between the upper seal support and the lower seal support. In still further aspects of the invention, a side seal is a contact side seal which runs and/or contacts the vertical surface of the lower seal support. In still further aspects of the invention, a non-contact seal is provided which rotates spaced from the surface of the a horizontal surface of the lower seal support. The non-contact seal may include two closely spaced fingers or times having lengths substantially longer than widths. This improves resiliency of tines, improving reliability.
These and other features of the invention will be apparent upon consideration of the following detailed description of preferred embodiments. Although the invention has been defined using the appended claims, these claims are exemplary in that the invention is intended to include the elements and steps described herein in any combination or subcombination. Accordingly, there are any number of alternative combinations for defining the invention, which incorporate one or more elements from the specification, including the description, claims, and drawings, in various combinations or subcombinations. It will be apparent to those skilled in the art of roller bearing seals, theory and design in light of the present specification, that alternate combinations and subcombinations of one or more aspects of the present invention, either alone or in combination with one or more elements and/or steps defined herein, may be utilized as modifications or alterations of the invention or as part of the invention. It is intended that the written description of the invention contained herein cover all such modifications and alterations. For example, in alternate aspects of the invention, the seal may include one or more of the water shield, the non-contact shield, the contacting side seal and/or the grease seal in any combination or subcombination.